Cluster file system support for extended network service addresses

ABSTRACT

A computer program product is provided for extending network services addresses. The computer program product comprises a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to identify a network event affecting a node of a sub-cluster of nodes of a network, wherein the node provides external access to the network using an Internet Protocol (IP) address. The program instructions are also executable by the processor to cause the processor to, in response to identifying the network event, identify an attribute associated with the IP address of the node. Finally, the program instructions are executable by the processor to cause the processor to, based on the attribute associated with the IP address of the node, determine whether to move the IP address of the node to another node of the sub-cluster.

BACKGROUND

The present invention relates to clustered file systems, and moreparticularly, this invention relates to the use of address attributes incloud storage systems and networks.

Clustered file systems provide a powerful homogenous view and access todiverse sources of storage. However, a major drawback to these systemsis that the easiest and most direct method for a user to access the filesystem data is from a node that is a direct member of the file systemcluster. To relax this constraint, services have been implemented on topof clustered file systems that export or externalize the clustered filesystem data. An example of this is Network File System (NFS) and ServerMessage Block (SMB) services, which may export the clustered filesystem. Users may then access the data from any computer systemimplementing these ubiquitous protocols.

Typically, this service export is associated with the concept of networkservice addresses. Clients to the external services connect to theclustered file system and the services running on the clustered filesystem through these network addresses. In most cases, the clients areunaware that they are connected to a cluster. In this environment,high-availability is ensured by implementing these service addresses asaliases attached to physical or virtual adapters. More than one node ofthe cluster is configured to support the network addresses. In the eventthat a cluster node currently configured with an address alias fails,then that address is moved to a healthy node. Clients detect thismovement and either directly, or transparently, reconnect to the healthycluster node through the same network address.

BRIEF SUMMARY

In one general embodiment, a computer program product is provided forextending network services addresses, the computer program productcomprising a computer readable storage medium having programinstructions embodied therewith, the program instructions executable bya processor to cause the processor to identify a network event affectinga node of a sub-cluster of nodes of a network, wherein the node providesexternal access to the network using an Internet Protocol (IP) address.The program instructions are also executable by the processor to causethe processor to, in response to identifying the network event, identifyan attribute associated with the IP address of the node. Finally, theprogram instructions are executable by the processor to cause theprocessor to, based on the attribute associated with the IP address ofthe node, determine whether to move the IP address of the node toanother node of the sub-cluster.

In another general embodiment, a computer program product is providedfor extending network services addresses, the computer program productcomprising a computer readable storage medium having programinstructions embodied therewith, the program instructions executable bya processor to cause the processor to group at least two nodes of aclustered file system into a sub-cluster, wherein each node in thesub-cluster provides at least one external service. The programinstructions executable by the processor also cause the processor todefine a network address attribute. Finally, the program instructionsexecutable by the processor cause the processor to associate the networkaddress attribute with an Internet Protocol (IP) address of one of thenodes of the sub-cluster, such that the one of the nodes of thesub-cluster provides the at least one external service at the IP addressin accordance with the network address attribute.

In yet another general embodiment, a system is provided, the systemcomprising a processor and logic integrated with and/or executable bythe processor, the logic configured to identify a network eventaffecting a node of a sub-cluster of nodes of a network, wherein thenode provides external access to the network using an Internet Protocol(IP) address. The logic is further configured to, in response toidentifying the network event, identify an attribute associated with theIP address of the node. The logic is also configured to, based on theattribute associated with the IP address of the node, determine whetherto move the IP address of the node to another node of the sub-cluster.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cloud computing node according to an embodiment of thepresent invention.

FIG. 2 depicts a cloud computing environment according to an embodimentof the present invention.

FIG. 3 depicts abstraction model layers according to an embodiment ofthe present invention.

FIG. 4 illustrates a method for providing clustered file system supportfor extended network service addresses, in accordance with oneembodiment.

FIG. 5 illustrates a method for providing clustered file system supportfor extended network service addresses, in accordance with anotherembodiment.

FIG. 6 illustrates a command line interface providing output regarding aclustered file system wherein attributes are assigned to networkaddresses, according to one embodiment.

FIG. 7 illustrates a command line interface for managing networkaddresses and attributes, according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

The following description discloses several embodiments for extendingnetwork service addresses.

In one general embodiment, a computer program product is provided forextending network services addresses, the computer program productcomprising a computer readable storage medium having programinstructions embodied therewith, the program instructions executable bya processor to cause the processor to identify a network event affectinga node of a sub-cluster of nodes of a network, wherein the node providesexternal access to the network using an Internet Protocol (IP) address.The program instructions are also executable by the processor to causethe processor to, in response to identifying the network event, identifyan attribute associated with the IP address of the node. Finally, theprogram instructions are executable by the processor to cause theprocessor to, based on the attribute associated with the IP address ofthe node, determine whether to move the IP address of the node toanother node of the sub-cluster.

In another general embodiment, a computer program product is providedfor extending network services addresses, the computer program productcomprising a computer readable storage medium having programinstructions embodied therewith, the program instructions executable bya processor to cause the processor to group at least two nodes of aclustered file system into a sub-cluster, wherein each node in thesub-cluster provides at least one external service. The programinstructions executable by the processor also cause the processor todefine a network address attribute. Finally, the program instructionsexecutable by the processor cause the processor to associate the networkaddress attribute with an Internet Protocol (IP) address of one of thenodes of the sub-cluster, such that the one of the nodes of thesub-cluster provides the at least one external service at the IP addressin accordance with the network address attribute.

In yet another general embodiment, a system is provided, the systemcomprising a processor and logic integrated with and/or executable bythe processor, the logic configured to identify a network eventaffecting a node of a sub-cluster of nodes of a network, wherein thenode provides external access to the network using an Internet Protocol(IP) address. The logic is further configured to, in response toidentifying the network event, identify an attribute associated with theIP address of the node. The logic is also configured to, based on theattribute associated with the IP address of the node, determine whetherto move the IP address of the node to another node of the sub-cluster.

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a high-erlevel of abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstateless-ness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 1, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 1, computer system/server 12 in cloud computing node 10is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Inter-connects (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethod-ologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Referring now to FIG. 2, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices MA-N shownin FIG. 2 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 3, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 2) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 3 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

The management layer 80 may also provide functionality for managing IPaddresses, implementing and managing IP address attributes, andutilizing the IP address attributes when responding to network events.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and mobile desktop 96.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a FPGA, etc. By executable by theprocessor, what is meant is that the logic is hardware logic; softwarelogic such as firmware, part of an operating system, part of anapplication program; etc., or some combination of hardware and softwarelogic that is accessible by the processor and configured to cause theprocessor to perform some functionality upon execution by the processor.Software logic may be stored on local and/or remote memory of any memorytype, as known in the art. Any processor known in the art may be used,such as a software processor module and/or a hardware processor such asan ASIC, a FPGA, a central processing unit (CPU), an integrated circuit(IC), a graphics processing unit (GPU), etc.

Now referring to FIG. 4, a flowchart of a method 400, for providingclustered file system support for extended network service addresses, isshown according to one embodiment. The method 400 may be performed inaccordance with the present invention in any of the environmentsdepicted in FIGS. 1-3, among others, in various embodiments. Of course,more or less operations than those specifically described in FIG. 4 maybe included in method 400, as would be understood by one of skill in theart upon reading the present descriptions.

Each of the steps of the method 400 may be performed by any suitablecomponent of the operating environment. For example, in variousembodiments, the method 400 may be partially or entirely performed by adata server or user device, or some other device having one or moreprocessors therein. The processor, e.g., processing circuit(s), chip(s),and/or module(s) implemented in hardware and/or software, and preferablyhaving at least one hardware component may be utilized in any device toperform one or more steps of the method 400. Illustrative processorsinclude, but are not limited to, a central processing unit (CPU), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), etc., combinations thereof, or any other suitablecomputing device known in the art.

At operation 402, a network event is identified. Further, the identifiednetwork event affects a node of a sub-cluster of a cluster of nodes of anetwork. Moreover, the affected node may provide external access to aclustered file system of the network using an Internet Protocol (IP)address. In other words, external clients may connect to the IP addressfor read/write access to the clustered file system hosted on the clusterof nodes. A clustered file system may include any file system that issimultaneously mounted by multiple services and/or nodes. Examples ofcommercial clustered file systems include: Lustre, Oracle Cluster FileSystem, Veritas Cluster File System, and GlusterFS (Linux).Additionally, the Cluster Trivial Data Base component of Samba alsoemploys network service addresses for fail over.

In one embodiment, the cluster may include servers that offer servicesto clients, and the clients access the services by connecting to one ormore IP addresses that are exported by nodes of the cluster. In such anembodiment, the clients may not connect to the servers themselves, butinstead the clients connect to nodes delegated to manage incomingconnections for the servers.

In various embodiments, it may be determined which nodes of a clusterare capable of supporting external services and exporting IP addressesfor external access by various clients. As used herein, an exported IPaddress may be any address that is made accessible to clients by a nodeso that the clients may, through the IP address, access resources of thecluster. For example, an exported IP address may be an IP address that aclient may connect to over the Internet for accessing resources of thecluster. In a given configuration, a cluster may include only one nodethat is capable of supporting external services and exporting IPaddresses. In another configuration, all of a plurality of nodes of acluster may be capable of supporting external services and exporting IPaddresses. The nodes of the cluster that are capable of supportingexternal services and exporting IP addresses may be logically defined asa sub-cluster, and the nodes of the sub-cluster may export the IPaddresses for connection by various clients.

As an example, in a given four-node cluster, if two of the nodes arecapable of supporting external services and exporting IP addresses, thenthose two nodes may be defined as a sub-cluster. Further, an applicationprogramming interface (API) may be provided to allow a user to assignthe IP addresses to the nodes, as well as to assign attributes to the IPaddresses, as discussed below.

The clients may include Network File System (NFS) clients, ServerMessage Block (SMB) clients, open stack clients, etc., that connect tothe respective service offered by the node at the IP address. Forexample, a SMB client may connect to the IP address for read/writeaccess of the clustered file system using a SMB service of the node.

In one embodiment, each of the nodes of a given sub-cluster may providethe same external services to any clients that are connected to itsexternal IP addresses. For example, a first one of the nodes of asub-cluster may provide SMB service, and a second node of thesub-cluster may also provide SMB service. Further, the clients of suchan embodiment may not care about which address or which node of thesub-cluster they are connected to for using the SMB service. Because ofthis, addresses may be configured uniformly in the cluster. Accordingly,when one of the nodes experiences a failure condition in such anembodiment, the node may be replaced by another one of the nodes of thesub-cluster in order to continue providing external services toconnected clients.

A given node of a sub-cluster may replace another node of thesub-cluster by moving one or more exported IP addresses to the givennode from the node it is replacing. As a result, a client connected atone of the IP addresses may follow its connection as the address ismoved in the sub-cluster. IP addresses may be moved between nodes toensure high availability, as well as for load balancing purposes whenthe load on one or more nodes exceeds a threshold. For example, if anode fails, then the external IP addresses of the node may be moved toone or more non-failed nodes, and clients may continue to access theclustered file system at the external IP addresses via the one or morenon-failed nodes. As another example, if a node provides SMB and NFSservices at two or more external IP addresses, and the node isoverloaded, then one of the external IP addresses may be moved toanother node to continue providing the respective service to therespective clients, while reducing the load on the node.

In another embodiment, each of the nodes of a sub-cluster may providedifferent external services to clients that are connected to itsexternal IP addresses. For example, a first one of the nodes of asub-cluster may provide SMB service, and a second node of thesub-cluster may provide NFS service. In such an embodiment, if the firstone of the nodes of the sub-cluster were to fail, the second node of thesub-cluster may not adequately replace the failed node because thesecond node of the sub-cluster does not provide the SMB service beingutilized by the failed node's connected clients.

In one embodiment, the network event identified at operation 402 mayinclude the failure of a node. In another embodiment, the network eventmay include a failure of an aspect of the network, such as aninterconnect between the node and another entity, such as a path,switch, router, gateway, etc. In yet another embodiment, the networkevent may include a heavy load. For example, the node of the sub-clustercould experience a load that exceeds a predefined threshold. The loadmay exceed the threshold due to the number of clients connected,processor workload, bandwidth, etc.

At operation 404, in response to identifying the network event, anattribute associated with the IP address of the node is identified. Theattribute may include any value stored in association with, or assignedto, the IP address that is utilized to determine a response to thenetwork event. For example, an action or response of a managementapplication to a circumstance that affects the IP address may bedetermined using the attribute.

As used herein, a management application may include any code thatevaluates one or more attributes associated with an IP address to make adetermination regarding a location of the IP address. For example, themanagement application may include failover code that is triggered inresponse to the failure of a node or network. As another example, themanagement application may include load balancing code that is triggeredwhen a load on a node reaches or exceeds a threshold, and the loadbalancing code is responsible for balancing the loads amongst nodes of acluster or sub-cluster. Thus, one or more management applications of aclustered file system may be responsible for assigning external IPaddresses, and moving these IP addresses between nodes in response tonetwork outages, failures, and loads.

Next, at operation 406, based on the attribute associated with the IPaddress of the node, it is determined whether to move the IP address ofthe node to another node of the sub-cluster. The movement of the IPaddress to another node of the sub-cluster may or may not be preventedby the attribute assigned to the IP address.

In one embodiment, a static attribute may indicate that an associatedaddress should not be moved under any circumstance. In other words, thestatic attribute may indicate that the associated IP address cannot bemoved from the node that currently exports the IP address. For example,if a given node is providing external services to clients at a given IPaddress assigned with a static attribute, and that node were to fail,then the management application would be prevented from moving theaddress to another node due to the static attribute. Thus, if the staticattribute is identified at operation 404, then any movement of the IPaddress is prevented.

As a consequence of the static attribute, any client connected to anexported IP address that is assigned the static attribute may bedisconnected from the clustered file system in the event of a failure ofthe node hosting the IP address. As a result, the client's access to theservice may be interrupted. In some embodiments, another address may beutilized by the client, in place of the address of the failed node, sothat the client may continue to access the clustered file system via adifferent node.

In this way, the static attribute may be utilized by a service that hasadded an external IP address to a network pool for a specific purpose,and does not want the IP address moved to another node in the event of afailure. Assignment of a static attribute to an IP address may alsoprevent movement of the IP address during a reboot operation.

In another embodiment, a sticky attribute may indicate that anassociated address should not be moved for load balancing purposes. Inother words, an IP address assigned the sticky attribute will not bemoved for load balancing reasons. Thus, if the sticky attribute isidentified at operation 404, then movement of the IP address to a newnode may be allowed if the network event affecting the node is a failureof the node. However, if the sticky attribute is identified at operation404, and the network event affecting the node is a heavy load, thenmovement of the IP address will be prevented. Consequently, themanagement application may be forced to move other addresses that arenot associated with the sticky attribute, or to allow the heavy load topersist on the node.

In a specific example, where a first node is assigned a first twoexternal IP addresses, and a second node is assigned a second twoexternal IP addresses, if a load on one of the two nodes is greater thana load on the other of the nodes by a predetermined threshold, thenmonitoring software may determine to move at least one of the externalIP addresses from the more heavily loaded node. In other words,monitoring software may attempt to balance the load between nodes in asub-cluster. However, if all of the external IP addresses have beenassigned a sticky attribute, then none of the external addresses may beavailable for movement for load balancing purposes. Accordingly, themonitoring software may identify and evaluate the attributes of theexternally served IP addresses of the nodes before attempting any loadbalancing operation. In the event that the monitoring softwareidentifies an over-loaded node serving an external IP address that maybe moved for load balancing reasons, then the monitoring software maymove the external IP address to another node of the sub-cluster.

The sticky attribute may be associated with an IP address when it iscostly or difficult to re-establish on a different node the servicesoffered at the IP address. Thus, the IP address should only be moved toa different node in the event of a failure of the currently exportingnode.

Any client connected to a service at an exported IP address when the IPaddress is moved from a first node to a second node may continueaccessing the clustered file system at the connected address via thesecond node without any service interruption. In other words, theclients may be moved with the address. Further, because access of theclients to the clustered file system is node independent, movement ofthe IP address between nodes may be transparent to the external clientsconnected to the clustered file system at the IP address.

In another embodiment, an affinity attribute may indicate that anassociated address has a preference for a particular node. In otherwords, the affinity attribute may indicate that the IP address it isassigned to should, when possible, be exported by non-preferred nodes.For example, if a first node is providing external services to clientsat a given IP address assigned an affinity attribute, and the first nodewere to experience a heavy load under which addresses are typicallymoved off the first node to other nodes, then the management applicationmay identify that the affinity attribute indicates an affinity of thegiven IP address for a second node. Thus, as a result, the given IPaddress may be moved to the second node in order to satisfy the affinityattribute assigned to the IP address, and to reduce the load on thefirst node.

The affinity attribute may be assigned to an IP address when the IPaddress should be, by default, associated with a particular node forvarious reasons. For example, if the IP address provides a uniqueservice, and it makes sense for all clients using the unique service toconnect to a particular node for reasons associated with geography orresource utilization, then the IP address may be assigned an affinityattribute that identifies an affinity for the particular node. This mayensure that the external IP address is always exported by the particularnode unless the node has failed or otherwise experiences reducedavailability. In this manner, clients that utilize the unique servicemay be funneled to the particular node. Affinity attributes may beevaluated on a regular basis (e.g., every n seconds, n minutes, etc.),independent of network failures/outages, to ensure that the affinityattributes are, when possible, satisfied.

In accordance with the above description, a clustered file system maymonitor and maintain (e.g., start, stop, etc.) external network IPaddresses. Further, clustered file system code may honor attributesassigned to the network IP addresses when responding to events such asnode failure, network failure, and/or heavy load. Accordingly, theseassigned attributes may control how the IP addresses are moved from nodeto node in response to different events affecting the cluster.

Now referring to FIG. 5, a flowchart of a method 500, for providingclustered file system support for extended network service addresses, isshown according to one embodiment. The method 500 may be performed inaccordance with the present invention in any of the environmentsdepicted in FIGS. 1-3, among others, in various embodiments. Of course,more or less operations than those specifically described in FIG. 5 maybe included in method 500, as would be understood by one of skill in theart upon reading the present descriptions.

Each of the steps of the method 500 may be performed by any suitablecomponent of the operating environment. For example, in variousembodiments, the method 500 may be partially or entirely performed by adata server or user device, or some other device having one or moreprocessors therein. The processor, e.g., processing circuit(s), chip(s),and/or module(s) implemented in hardware and/or software, and preferablyhaving at least one hardware component may be utilized in any device toperform one or more steps of the method 500. Illustrative processorsinclude, but are not limited to, a central processing unit (CPU), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), etc., combinations thereof, or any other suitablecomputing device known in the art.

As shown in operation 502, at least two nodes of a clustered file systemare grouped into a sub-cluster. Further, each of the nodes in thesub-cluster provides at least one external service. Accordingly, thesub-cluster may be logically defined to include clustered file systemnodes that have external network access.

In addition, at operation 504, a network address attribute is defined.Defining a network address attribute includes any action that enables amanagement application to identify the network address attribute, andthen operate in a predefined manner on an IP address assigned theattribute.

In various embodiments, more than one network address attribute may bedefined. As noted above, the network address attribute may include anattribute to prevent movement of an IP address between nodes under anycircumstance, such as a static attribute. Still yet, the network addressattribute may include an attribute to prevent movement of an IP addressbetween nodes due to load balancing operations, such as a stickyattribute. Of course, the attribute defined at operation 504 may includeany of the attributes discussed above in the context of FIG. 4.

In yet another embodiment, a multicast attribute may indicate that anassociated address is a multicast address. In such an embodiment, themulticast attribute may ensure that multicast IP addresses are onlyexported by specific nodes.

In one embodiment, each IP address may be associated with a protocolattribute that indicates protocols or services available at the IPaddress. In other words, for an IP address that is being exported by anode, a protocol attribute assigned to the IP address may indicate theservices available to clients using the IP address. For example, aprotocol attribute assigned to an IP address exported by a given nodemay indicate that SMB is being used by clients attached to the node atthat address. Moreover, the protocol attribute may be updateddynamically, in response to clients connecting. For example, in responseto a first client connecting at the IP address and accessing a clusteredfile system using SMB, the assigned protocol attribute may be updated toreflect usage of SMB. Accordingly, if the node were to fail, amanagement application may determine, using the protocol attribute, thatthe IP address should be moved to another node that is alreadysupporting access to the clustered file system using SMB.

Similarly, if the node were to fail while exporting an IP address thatis assigned a protocol attribute indicating the connection of both SMBand NFS clients, then the management application may determine that theIP address should be moved to another node that is already supportingaccess to the clustered file system using both SMB and NFS. In thismanner, the external IP addresses of failed nodes may be reliably movedto non-failing nodes that fully support the services used by the clientsof the failing node.

In another embodiment, the protocol attribute associated with anexported IP address may not be dynamically updated based on connectedclients, but may instead be static. In other words, the protocolattribute assigned to an exported IP address may indicate that only alimited sub-set of services are available at the IP address (e.g., onlySMB, only NFS, etc.). A management application may utilize the protocolattribute of a given IP address to determine which other IP addressesbeing exported by other nodes of the cluster also make available thesame services.

The management application may need to make such a determination when anode has failed, and one or more IP addresses exported by the failingnode may not be moved to non-failing nodes. Thus the managementapplication may need to identify new IP addresses supporting theservices utilized by the clients of the failing node. For example, ifSMB service is not active on all nodes of a clustered file system, and anode that is exporting IP addresses for usage by SMB clients fails, thenthe protocol attribute may enable quick identification of one or moreother external IP addresses on other nodes that support SMB clients.Accordingly, the protocol attribute may make it such that it is notnecessary to activate all services on all nodes of a clustered filesystem, and thereby preserve system resources.

In one embodiment, an activation attribute may indicate that anassociated IP address should only be exported when one or moreparticular nodes are active. In other words, an activation attribute maybe assigned to an IP address for limiting the exportation of the IPaddress to only when the one or more particular nodes are active. As aresult, the IP address may only be exported and made available toexternal clients when the one or more particular nodes are operational.The activation attribute may be employed where aspects of an executingapplication require a specific node presence and/or node configuration.For example, where the executing application requires resources onlyavailable between a limited sub-set of nodes. When the specific nodepresence and/or node configuration is not present, then the executingapplication and/or the clients connected at the exported IP address mayexperience errors. Accordingly, to avoid wasting resources, the IPaddress is not made available to external clients unless the one or moreparticular nodes identified by an assigned activation attribute areenabled.

In various embodiments, the attributes associated with the external IPaddresses of the nodes may be stored in a repository. For example, eachexternal IP address may be stored in the repository in association withany attribute(s) that it has been assigned. As an option, the attributesmay be stored in a table or database of the repository. Further, theattributes may be stored as one or more text strings.

Next, at operation 506, the attribute is associated with an IP addressof one of the nodes of the sub-cluster. Based on the association of theattribute with the IP address of the node, the node of the sub-clusterprovides the at least one external service at the IP address inaccordance with the attribute. In various embodiments, associating thenetwork address attribute with the IP address includes assigning theattribute to the IP address.

In one embodiment, commands may be implemented to allow users to add,delete, and/or move IP addresses to a sub-cluster pool. Further,commands may allow users to add, delete, and/or move an IP addressto/from a particular node. Commands may also allow users to manuallyassign one or more attributes to an IP address. The IP address may beexported by a node for external access by one or more clients.

In one embodiment, clustered file system code may be modified todynamically set network address attributes, such as an affinityattribute for a specific service, such as SMB or NFS.

In some embodiments, a clustered file system may be responsible forassigning and failing-over exported IP addresses between nodes of thesub-cluster grouped at operation 502. The clustered file system mayassign and fail-over the IP addresses in response to network events,such as node failure, network failure, and heavy load. Accordingly, theclustered file system may be configured to assign and fail-over the IPaddresses in accordance with the network address attributes assigned tothe IP addresses.

Thus, a list of one or more attributes may be assigned to each of theexternal IP addresses. These attributes may be assigned staticallyand/or dynamically, and control the behavior of a clustered file systemin the event of failures or other events.

As noted above, in various embodiments, a cluster may include one ormore nodes that provide access to a clustered file system, and thecluster may implement service address pools. The clustered file systemmay allow management and monitoring of the addresses in the pools, inaddition to recovery methods. More than one node of a cluster may beconfigured to support the network addresses. In the event that a clusternode currently configured with an address alias fails, then that addressmay be moved to a healthy node. Clients may detect this movement andeither directly, or transparently, reconnect to the healthy cluster nodethrough the same network address. However, some services may wish to addaddresses to a network pool for network management, and do not want, inthe event of a failure, the addresses to be moved to other nodes in thecluster. The methods described hereinabove may enable the customizedconfiguration of cluster management and monitoring in accordance withsuch preferences.

FIG. 6 depicts a command line interface 600 providing output regarding aclustered file system wherein attributes are assigned to networkaddresses, according to one embodiment. As an option, the presentcommand line interface 600 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchcommand line interface 600 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the command line interface 600 presented herein may be used inany desired environment.

As shown in the command line interface 600, a user has requested, for aclustered file system, a list of addresses and associated attributes ofthe nodes of the clustered file system. In response, the command lineinterface 600 has provided output that indicates the configuration offour nodes (1-4), as well as a name for each of the nodes. The commandline interface 600 output has provided an IP address for accessing eachof the four nodes from an internal network of the clustered file system.Moreover, for each of the four nodes, the command line interface 600 haslisted one or more IP addresses that the node is exporting for access byexternal clients, and any attribute assigned to each of the exported IPaddresses.

Specifically, the command line interface 600 shows that Node 1 isexporting two external IP addresses, 5.6.7.2 and 6.7.8.6, and furthershows that external IP address 6.7.8.6 has been assigned attribute1. Thecommand line interface 600 also shows that Node 2 is exporting twoexternal IP addresses, 5.6.7.1 and 6.7.8.5, and further shows thatexternal IP address 6.7.8.5 has been assigned attribute2. Additionally,the command line interface 600 shows that Node 3 is exporting twoexternal IP addresses, 5.6.7.3 and 6.7.8.7, and further shows thatexternal IP address 6.7.8.7 has been assigned attribute3. Finally, thecommand line interface 600 shows that Node 4 is exporting two externalIP addresses, 5.6.7.4 and 6.7.8.9, and further shows that external IPaddress 6.7.8.9 has been assigned attribute4.

Each of attribute1, attribute2, attribute3, and attribute4 may includeany of the attributes discussed above in the context of FIGS. 4-5, suchas, without limitation, the sticky attribute, the static attribute, theaffinity attribute, the protocol attribute, etc.

Accordingly, one or more management applications may utilize theassignment of attribute1, attribute2, attribute3, and attribute4 to Node1, Node, 2, Node 3, and Node 4, respectively, when managing the nodes,such as when determining whether to move the external IP addressesbetween the nodes in response to network events, such as node failures,network failures, and heavy loads.

While each of Node 1, Node, 2, Node 3, and Node 4 are shown in FIG. 6 tobe respectively exporting only one IP address that is assigned anattribute, it is contemplated that more than one address (i.e., a rangeof addresses) may be assigned a single attribute. For example, alladdresses being exported by a node may be assigned a given attribute. Itis also contemplated that different IP addresses being exported by agiven node may be assigned different attributes. For example, a first IPaddress being exported by Node 1 may be assigned a first attribute, anda second IP address being exported by Node 1 may be assigned a secondattribute different than the first attribute.

Additionally, where the attributes do not conflict, an external IPaddress may be assigned more than one attribute. For example, a givennode may export an IP address that has been assigned each of a stickyattribute (i.e., to prevent movement of the IP address to other nodesexcept for during a failover condition) and a protocol attribute (i.e.,to aid in tracking the services being utilized by clients connected atthe IP address).

FIG. 7 illustrates a command line interface 700 for managing networkaddresses and attributes, according to one embodiment. As an option, thepresent command line interface 700 may be implemented in conjunctionwith features from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchcommand line interface 700 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the command line interface 700 presented herein may be used inany desired environment.

As shown in the command line interface 700, a user may add external IPaddresses to a network pool, and further may remove external IPaddresses from the network pool. Also shown in the command lineinterface 700, the user may assign attributes to one or more of theexternal IP addresses.

As shown in the command line interface 700, specifically, the user hasadded external IP address 6.7.8.6 to the pool of external IP addresses,and at the same time assigned attribute1 to the IP address. Also, theuser has added external IP address 6.7.8.5 to the pool of external IPaddresses, and at the same time assigned attribute2 to the IP address.Additionally, the user has added external IP address 6.7.8.7 to the poolof external IP addresses, and at the same time assigned attribute3 tothe IP address. Moreover, the user has added external IP address 6.7.8.9to the pool of external IP addresses, and at the same time assignedattribute4 to the IP address. Finally, the user has removed external IPaddresses 6.7.8.3 and 6.7.8.4 from the pool of external IP addresses. Asa result, the clustered file system otherwise available at the activeexternal addresses may no longer be accessed by clients using the IPaddresses 6.7.8.3 and 6.7.8.4.

In this way, a user, such as an administrator, may add one or moreaddresses to a pool of external IP addresses. Further, although notshown, the user may further assign the external IP addresses toparticular nodes of a sub-cluster that are eligible to export servicesto external clients. Through use of the command line interface, the usermay dynamically configure the external IP addresses, and their assignedattributes, at any time.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer to offer service on demand.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A computer program product for extending network services addresses, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to: identify, by the processor, a network event affecting a node of a sub-cluster of nodes of a network, wherein the node provides external access to the network using an Internet Protocol (IP) address; in response to identifying the network event, identify, by the processor, an attribute associated with the IP address of the node; and based on the attribute associated with the IP address of the node, determine, by the processor, whether to move the IP address of the node to another node of the sub-cluster.
 2. The computer program product as recited in claim 1, wherein the attribute is assigned to the IP address of the node.
 3. The computer program product as recited in claim 2, wherein the network event includes a failure of the node.
 4. The computer program product as recited in claim 3, wherein the attribute includes a static attribute assigned to the IP address of the node, the static attribute preventing movement of the IP address to the other node of the sub-cluster in response to the failure of the node.
 5. The computer program product as recited in claim 3, wherein the attribute includes a sticky attribute assigned to the IP address of the node that prevents movement of the IP address to the other node in response to a load on the node exceeding a threshold.
 6. The computer program product as recited in claim 5, wherein the IP address assigned the sticky attribute is moved to the other node of the sub-cluster in response to the failure of the node.
 7. The computer program product as recited in claim 2, wherein the network event includes a load on the node exceeding a threshold.
 8. The computer program product as recited in claim 7, wherein the attribute includes a static attribute assigned to the IP address of the node, the static attribute preventing movement of the IP address to the other node of the sub-cluster in response to the load on the node exceeding the threshold.
 9. The computer program product as recited in claim 7, wherein the attribute includes a sticky attribute assigned to the IP address of the node, the sticky attribute preventing movement of the IP address to the other node in response to the load on the node exceeding the threshold.
 10. A computer program product for extending network services addresses, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to: group, by the processor, at least two nodes of a clustered file system into a sub-cluster, wherein each node in the sub-cluster provides at least one external service; define, by the processor, a network address attribute; and associate, by the processor, the network address attribute with an Internet Protocol (IP) address of one of the nodes of the sub-cluster, such that the one of the nodes of the sub-cluster provides the at least one external service at the IP address in accordance with the network address attribute.
 11. The computer program product as recited in claim 10, wherein the IP address is exported by the one of the nodes of the sub-cluster, and the network address attribute is assigned to the IP address of the one of the nodes of the sub-cluster.
 12. The computer program product as recited in claim 11, wherein the network address attribute includes a static attribute, the static attribute preventing movement of the IP address to another node of the sub-cluster in response to a failure of the one of the nodes of the sub-cluster.
 13. The computer program product as recited in claim 11, wherein the network address attribute includes a sticky attribute, the sticky attribute preventing movement of the IP address to another node of the sub-cluster in response to a load on the one of the nodes of the sub-cluster exceeding a threshold.
 14. The computer program product as recited in claim 11, wherein the network address attribute includes a protocol attribute, the protocol attribute being updated dynamically in response to clients connecting to the IP address, wherein the protocol attribute indicates at least one protocol of the at least one external service being used by the clients connected to the one of the nodes of the sub-cluster at the IP address.
 15. The computer program product as recited in claim 11, wherein the network address attribute includes a protocol attribute, the protocol attribute indicating a limited sub-set of external services that is available to clients at the IP address.
 16. The computer program product as recited in claim 11, wherein the network address attribute includes an affinity attribute, the affinity attribute indicating an affinity of the IP address for a particular node of the sub-cluster.
 17. The computer program product as recited in claim 11, wherein the network address attribute includes a multicast attribute, the multicast attribute indicating that the IP address is a multicast address.
 18. The computer program product as recited in claim 11, wherein the network address attribute includes an activation attribute, the activation attribute limiting exportation of the IP address, by the one of the nodes of the sub-cluster, to only when one or more particular nodes are active.
 19. A system, comprising: a processor and logic integrated with and/or executable by the processor, the logic being configured to: identify a network event affecting a node of a sub-cluster of nodes of a network, wherein the node provides external access to the network using an Internet Protocol (IP) address; in response to identifying the network event, identify an attribute associated with the IP address of the node; and based on the attribute associated with the IP address of the node, determine whether to move the IP address of the node to another node of the sub-cluster.
 20. The system as recited in claim 19, wherein the attribute includes a static attribute assigned to the IP address of the node, the static attribute preventing movement of the IP address to the other node of the sub-cluster in response to a failure of the node. 